1. Field of the Invention
This invention relates to methods of purifying water, particularly purifying the water used in hot tubs and the like, and most particularly to methods of purifying hot tubs not involving addition of substantial amounts of dissolved chemicals in the water.
2. State of the Art
Recreational users of hot tubs, spas, and whirl pool baths of various sorts, hereinafter generically referred to as hot tubs, enjoy and use them more than ever. At one time or another, most of the users have noticed the nearly universal problem affecting water quality that most hot tubs have: maintaining clear, sanitary and odor free water after frequent uses.
Many solutions have been tried to maintain the water quality. One common method is the brute force method of adding large amounts of chlorine to the water. This tends to give hot tubs a distinct chlorine odor and can, at times be strong enough to cause mild respiratory distress. Moreover, the amount of chlorine tends to become so concentrated, that, with time all of the water in the hot tub must be replaced.
Another solution tried is the on-site generation of ozone gas (O.sub.3). Ozone is a toxic gas, more toxic than chlorine, and it must be generated on site, requiring expensive and troublesome equipment to generate. It is troublesome to regulate, and production of more than the required amount can cause mucus membrane and eye irritation in the users of the equipment, and in large enough quantities, over production can erode covers used to protect the hot tub between uses. Even so, rarely can the generation equipment meet the demands for enough ozone to maintain the water quality placed on the system by frequent use of several people.
Yet another type of purification used is the ionization method. In this approach to the problem an electric current is passed between two electrodes, usually silver and copper, immersed in he water. This method leaves a copper residua in the water, indeed that is one of the reasons the method works. But copper can cause stains on the plaster used for the inside of the hot tub.
Combinations of the ozone method and the ionization method have been tried and the results have been poor. The resulting system is very expensive, the treatment irritating to the users, and the treatment is not long lasting.
Whatever method is used to purify the hot tub, the water in an average hot tub must be changed every three months or so and the attempt at purification process must start anew.
The hot tub user needs a better method to assure that the water contacting his body is pure, clean, and pleasant to be in.